#region Copyright & License

//
// Copyright 2001-2005 The Apache Software Foundation
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

#endregion

using log4net.Util;

namespace log4net {
  /// <summary>
  /// The log4net Thread Context.
  /// </summary>
  /// <remarks>
  /// <para>
  /// The <c>ThreadContext</c> provides a location for thread specific debugging 
  /// information to be stored.
  /// The <c>ThreadContext</c> properties override any <see cref="GlobalContext"/>
  /// properties with the same name.
  /// </para>
  /// <para>
  /// The thread context has a properties map and a stack.
  /// The properties and stack can 
  /// be included in the output of log messages. The <see cref="log4net.Layout.PatternLayout"/>
  /// supports selecting and outputting these properties.
  /// </para>
  /// <para>
  /// The Thread Context provides a diagnostic context for the current thread. 
  /// This is an instrument for distinguishing interleaved log
  /// output from different sources. Log output is typically interleaved
  /// when a server handles multiple clients near-simultaneously.
  /// </para>
  /// <para>
  /// The Thread Context is managed on a per thread basis.
  /// </para>
  /// </remarks>
  /// <example>Example of using the thread context properties to store a username.
  /// <code lang="C#">
  /// ThreadContext.Properties["user"] = userName;
  ///	log.Info("This log message has a ThreadContext Property called 'user'");
  /// </code>
  /// </example>
  /// <example>Example of how to push a message into the context stack
  /// <code lang="C#">
  ///	using(ThreadContext.Stacks["NDC"].Push("my context message"))
  ///	{
  ///		log.Info("This log message has a ThreadContext Stack message that includes 'my context message'");
  ///	
  ///	} // at the end of the using block the message is automatically popped 
  /// </code>
  /// </example>
  /// <threadsafety static="true" instance="true" />
  /// <author>Nicko Cadell</author>
  public sealed class ThreadContext {
    #region Private Instance Constructors

    /// <summary>
    /// Private Constructor. 
    /// </summary>
    /// <remarks>
    /// <para>
    /// Uses a private access modifier to prevent instantiation of this class.
    /// </para>
    /// </remarks>
    ThreadContext() {}

    #endregion Private Instance Constructors

    #region Public Static Properties

    /// <summary>
    /// The thread properties map
    /// </summary>
    /// <value>
    /// The thread properties map
    /// </value>
    /// <remarks>
    /// <para>
    /// The <c>ThreadContext</c> properties override any <see cref="GlobalContext"/>
    /// properties with the same name.
    /// </para>
    /// </remarks>
    public static ThreadContextProperties Properties {
      get { return s_properties; }
    }

    /// <summary>
    /// The thread stacks
    /// </summary>
    /// <value>
    /// stack map
    /// </value>
    /// <remarks>
    /// <para>
    /// The thread local stacks.
    /// </para>
    /// </remarks>
    public static ThreadContextStacks Stacks {
      get { return s_stacks; }
    }

    #endregion Public Static Properties

    #region Private Static Fields

    /// <summary>
    /// The thread context properties instance
    /// </summary>
    static readonly ThreadContextProperties s_properties = new ThreadContextProperties();

    /// <summary>
    /// The thread context stacks instance
    /// </summary>
    static readonly ThreadContextStacks s_stacks = new ThreadContextStacks(s_properties);

    #endregion Private Static Fields
  }
}